OCD technical question regarding charging practices.
In the summer I regularly drive to a cottage. In terms of charging I can either arrive at the destination with ~5% charge left and recharge overnight. Alternatively I can stop at a supercharger, partially top up and arrive at the destination with ~ 50% charge and then recharge the rest overnight. Im interested in which of the two would be better overall. Basically a tradeoff between supercharging to avoid a full cycle charge (or vice versa). Just wondering which option would be better for the health of the battery.
Realistically I appreciate the angle of "just enjoy the car" and that this may have little to no difference in terms of real world effects, but was interested none the less.
TIA
It is not an easy question to answer in one line. In most cases the supercharging session will wear more than a large cycle.
Your question includes two full charges, and try to reduce the wear by making the cycle smaller?
in most cases the wear from a big cycle is mainly the high SOC part, so going 100-50-100-50 do not save much cyclic wear compared to 100-0%
Supercharging without preconditioning will cause more wear than a large cycle.
-> Preheat, always is my advice.
Supercharging cause different wear depending on within what SOC range the supercharging is done. Low SOC causes much less wear than high SOC.
-> Use the low SOC region (and use a complete preconditioning) to reduce the supercharging wear. OP question seems include a about 50 to 100% SOC supercharge.
The negative effect of supercharging is lithium plating, and there is clear evidence from the research that using low SOC has a self repairing effect that returns lithium from the clogged lithium plates.
@AlanSubie4Life more or less nailed it in the way I would do it, 50-5%, if selecting the supercharging way.
As for the calendar aging mentioned, the extra calendar aging charging to 100% and driving it down to low SOC without big delay is negligible. We can charge to 100%, from low SOC, drive the car down to 0% and have a average during this time of about 50%
The OP implies using high SOC normally, so the calendar aging might be less this day than any other day anyway.
arrive at the destination with ~ 50% charge and then recharge the rest overnight
As supercharging do wear more than AC charging, we need to compare one ”big nice cycle” with one smaller nice cycle plus one Supercharging cycle at relative high SOC.
The amber dashed line is about 100% down to 5-10% or so. 1250 FCE cycles cause 20-25% degradation.
The grey dashed line is about 50% to 5-10% or so. 1250 FCE cause about 10% degradation.
The high SOC cycles causes double degradation compared to low SOC cycles.
Here’s the wear from supercharging to 100% (4.2V) and 90% (4.1V). The grey lines is standard charging somewhere comparable to AC charging. The amber dashed line is discharge down to 5-10% and the dashed grey is standard charging comparable to AC charging discharged down to 5-10%.
We can see that the amplitude of the discharging is about five times worse than standard charging.
This is somehow the worst scenario:
Supercharging to high SOC, and I do not remember if the cells was preconditioned.
Supercharging in the lower region would reeduce the wear, but still its probably more than the double using full cycles.
